Module 10
NAT
Why a whole home shares one public address. Step packets through a translator, watch ports get rewritten and see the table that makes replies find their way back.
Start lesson 1
Why can a whole home share one address? · 7 min · free, no account
NetworkOpen now
What you'll operate
- Private and public addresses
- Port address translation
- The translation table
- lessons
- 6
- minutes
- 49
Lessons in this module
- 1Why can a whole home share one address?Follow one packet out of a home network and back, and see which address the internet really talks to.Free, no account7 min
- 2How do replies reach the right device?Two devices share one public address. See how port numbers and a table keep their conversations apart.Plus8 min
- 3What exactly does the translator rewrite?Follow a TCP handshake through the router field by field, checksums included, then see what a ping has in place of ports.Plus8 min
- 4Why can't the internet reach in?See why a packet nobody asked for stops at the router, open one door with a port forward, and learn why none of this makes NAT a firewall.Plus9 min
- 5How long does a table entry live?Watch an idle entry expire, work out what keeps one alive, and recognize the connections that die when nothing is sent.Plus8 min
- 6What does NAT break?Find the protocols that trip over translation, watch two phones punch a hole to reach each other, and learn to spot a second translator at your provider.Plus9 min
Lesson 1 is open to everyone, with no account. The other lessons in this module are part of Plus.